Refrigeration apparatus and method



NovQZl, 1939. E. RQ QLFERT 2,180,493

REFRIGERATION APPARATUS AND METHOD Filed A ril 50, 1938 s Sheets-Sheet 1 I 4 INVENTDR.

EuwnaoRwou-znr. s I 4 l Fla. 1. ATTORNKJ Nov. 21, 1939. wo 2,180,493

REFRIGERATION APPARATUS AND METHOD Filed April 30, 1938 3 Sheets-Sheet 2 INVEN TOR. 5s EDWARD RWOLFERT.

ATTORN s.

NOV. 21, 1939.- R, wo T 7 2,180,493

REFRIGERATION APPARATUS AND METHOD Filed April 30, 1938 s Sheets-Sheet s FIG. 5.

F'IG.6.

INVENTOR. EDWARD R.WOLFERT.

BY Arromvgs.

Patented Nov. 21, 1939 NT OFFICE REFRIGERATION Assumes AND i METHOD f Edward B, W olfert, Springfield; assignor to 5 Westinghouse Electric & Manufacturing Com- Pennsylvania ny, Pittsburgh, Paula; corporation of Application April 30, 1938,Serial 205,350 1 My invention relates to refrigerating systems and method, and particularly to refrigerating systems wherein "the refrigerant'compressor' and motorfor driving the same are enclosed ina fiu'id-tight'casing. This-application is a continuation in part of subject-matter divided from my application-Serial No. 98,742, filed-August 31, 1936.

It is an object of'my invention-toprovide an improved cooling system yfora' motorj-compressor unit of this type wherein the refrigerant fluid of therefrigeratingsystem is employed as a heattransfer agent, for dissipating the heat of the motor. 1

It, is another a sealed motor-compressor .unit by effecting a forced circulation of cool refrigerant gas over heated portions of the unit.- 1

It is still another object of my invention to 20 convey refrigerant suction gas from the low pressure side'of the refrigerating system directlyv to the compressor and at the same time to maintain an atmosphere of low pressure refrigerant. gas in the fluid-tight casing enclosing the motor and 25 compressor.

It is a further object of my invention to varythe cooling effect of the lowpressure refrigerant gas which is forcibly circulatedin the sealed. casing of a motor-compressor unit in proportion to 30 the refrigeration load on the unit, and-to also decrease thepower required for circulating the gas when the motor-compressor unit is lightly loaded.

These and other objects are efiected by my invention, as will be apparent from the following description and claims taken inconnection with the accompanying drawings, and forming a part of this application, in which:

Fig. 1 is a diagrammatic view of a closed refrigerating system embodying a sealed motor-com 4o pressorunit;

Fig. 2 is a sectional view of the sealed motorcompressor unit taken on line 11- 11 of Fig. 3; Fig. 3 is a longitudinal sectional view of the a portion objeotvof my: invention to cool Fig. 4 is a view ofthe motor endof themotorv the cylinder head suction-and discharge passages in'the crank case.

Referring specificallyto the drawings for a';

detailed description of my invention, in Fig. 1-,

numeral I designates generally a"motor-com1 receiverfj 3:: "an

press'or which is a part of a closed refrigerating'sjystemfembodying a condenser 2, 'a'liquid re- Iceivexj 3 n 'd' an evaporator 'or low pressure sidei4,

with arr-expansion valve --5. disposed between the vaporator. 4. A discharge con- 5 fs'sed refrigerantgas and a suc- 1 for vaporized I refrigerant gas 1 are ondenser 2 and evaporator 4, a l p an are connected to the motor compress?) um in a manner hereinafter, delo detail The operation oftherefrigerat' j i ollows: Refrigerantgas'is comfotor-compressor unit I andis die 1 cheer 2 through discharge conduit ornprei edges is condensed in the connd dr ns to the liquid receiver 3. tpasses through the expansion e p 'ates-in 'the' evaporator thusv and the vaporized low pressure,

frigerant gas is then returned to the moto I, 'ressor unit I through suction conduitfl eu on the cycle is repeated. The system primarily designed for operation at frigerationrloads, so that the 1 suction e 'aries considerably,- which in turn: more es n decreases the amount of work which i n'ust formed by the motor and the .P. chamber 11; which embers are in free'and open,

communication througha passage l 8 in the parti- 3 "h motor, generall dicated at I9, is contained in the'motor ch ber l1 and acompressor generallyfdesignated at 2lis contained in the com pre'ssor chamber [6. A'drive shaft ,zr co n fts' the 'motoNW-and' compressor *2! -,*anlc lf bearing and 30 provided in the end cover member 13f rid" era inane-partition"u'ares 'ctiveiv;supisdrtith sha'lft12 p 5 mb "'reciprocateden'thecylinders 24 by means of crank p0rtions*'26i"of the shaft has I nn c in *-rods""21 "wmehconnect the pie withtheirrspectiv'e rikpd rtionsfof the shaft 22.; a pan of valve mates; gen rally in- W dicatdat fljare clamped hetween the" cylin'ders 24 linder my shown in i Fig. 5, the valve 'plats" 28 charge and suction ports are disposed on opposite sides of the vertical center line of the disc for a purpose hereinafter described. The valves used are of the flexible metal strip type and a complete description of the construction and operation of the valves will be found in the patent to Meyer, No. 1,341,145.

As best shown in Figs. 2 and 6, the cylinder casting 20 is provided with an inlet gas passage 40 which isconnected to the suction conduit E from the evaporator t. The inlet passage 40 communicates with an oil separating chamber or manifold 40a which in turn communicates with the compressor chamber it through a passage 4 I, and with the cylinder head 29 through a'passage o 42 in the cylinder casting and through a passage 43 formed by a gasketed ring 44 clamped between the head 29 and the cylinder casting 2d.

- The passage 42 constitutes therefrigerant gas pended claims.

inlet of the compressor referred to in the ap- Lubricant separated from the suction gas in chamber a drains through passage to a lubricant reservoir 64. The suction gas then passes througha passage 45 in the cylinderhead and through passages 46 to the suction chambers 41 of the cylinder head. When the pistons 25 move downwardly, the suction gas passes through the valve plate 28 'into-the cylinders 24, the discharge ports 28a being closed at this time, and the suction ports 28b being open. The cylinder head 29 is provided with a partition 48 which seats tightly on the valve plate 28 dividing the cylinder head into compression chambers 49 and suction chambers 41, and separating the discharge ports 28a from the suction ports 28b. When the piston 25 moves upwardly in the cylinders 24, the suction ports 280 are closed and the discharge port 28a are open, admitting compressed gas to the compression chamber 69. Discharge gas is then conveyed through passages N and 5| in the cylinder head and through a pas- .sage 52 also formed by a gasketed ring 44 to a passage 53 in the cylinder casting 20, and thence through the discharge conduit 6 to the coninto the sealed casing H.

other through the passage ill in the partition Id,

as best shown in Fig. 3.

It will be apparent, therefore, that the refrigerant gas present in the sealed casing II is supplied thereto from the closed refrigerating system, and is being constantly circulated through the sealed casing. Furthermore. the density of the low pressure gas in the sealed casing always corresponds to the density of the gas in the low pressure side of the system, which is dependent on refrigeration load ,or suction pressure. However, most of the refrigerant gas returningirom the evaporator 4 is conveyed directly to the inlet of the compressor 2i and does not enter theremainder of the sealed casing ll. Therefore, the majority of the suction gas does not come into contact with the hot portions of the motor is and compressor 2| which are within the sealed casing. As a result, the suction gas is not superheated and the efficiency of the refrigerating system is materially increased.

resulting in contamination of lubricant and possible starving of the evaporator of refrigerant. With low pressure refrigerant gas in the sealed casing, a cooling fluid, such as water, may cool parts of the apparatus to temperatures, for example, below room temperature, in a system utilizing an air cooled condenser, without condensing refrigerant in the sealed casing. It is possible, therefore, to produce more cooling of the apparatus contained in the sealedcasing than could be achieved with high pressure gas therein.

Themotor l9 comprises a generally polygonally shaped stator 5e which is pressed into the cylindrical motor portion of the main frame l2. As shown in Fig. 4, the stator stampings preferably contact the main frame l2 at four points 55,1eaving passages 56 between the stator and the rotor.

As will be apparent, any generally polygonaliy shaped stator will provide the passages 66. Field windings 51 extend from both ends of the stator and are out of contact with the. sealed casing II.

The motor is also provided with a rotor 58 whichis connected to the drive shaft 22 in any convenient manner. A gap 59 is present between the stator M and the rotor 58.

As best shown in Fig. 3, the motor portion of the main frame member is provided with a passage or jacket 60 for cooling water for cooling the motor l9. Cooling water is circulated through the jacket 60 in any suitable manner well understood in the art through water inlet conduit 60a and water outlet conduit 80b.

A large portion of the heat of .the motor I9 is transmitted directly to the cooling water in the Jacket 60 by conduction through the points of contact 55 of the polygonal stator with the sealed casing II. it has been found that insumcient cooling of the motor is effected when the above heat transmittal is alone relied n points of contact 55 of the stator 54.

In order to assist in removing heat from the remote portions of the stator 54 and from' the rotor 58, the rotor is provided with a fan 8| preferably on one side thereof, and'with passages 82 extending through the rotor 58. The fan 6|, as shown in Figs. 3 and 4, is formed of a plurality However, in machines of this type,-

I n, as the rotor and the a field windings of the stator are remote from the of blades on the end of the rotor 58. The refrigerant gas present in the sealed casing which is derived from the crankcase of the compressor 9 is circulated by the fan 6|, the arrows in Fig. 1

showing the gas circulation first through the pas- -fsa"ges 56 between the stator 54 and the inner-.wall I! of the sealed casing ll opposite the water jacket 60, where heat is absorbed from the gas by the cool water in the Jacket 60. The cooled refrigerant gas is then forced over the field windings 51 at the compressor end of the motor, in a parallel path through'the passages 62 in the rotor 58 and through the air gap 59, through the fan SI and over the field windings 51 at the outboard ner, the motor I9 may be heavily loaded without overheating, since the cooled gas passing over the field windings, through the passages in the rotor and through the air gap absorbs heat from portions of the motor remote from points of contact of the motor and the water-jacketed casing.

As-statecl hereinbefore, it is an important feature of my invention to proportion the power required by the fan 6| and the cooling effect thereof to the refrigeration load. This may be accomplished by circulating, interiorly of the sealed casing, low pressure gas which varies in pressure with refrigeration load.

The following facts are first pointed out: First, the power input to the fan 6| is proportional to gasdensity and the gas density of the low pressure gas depends on suction pressure, or refrigeration load. Secondly, the cooling effect or heat transfer rate of the moving stream of gas varies approximately'a's the .7 power of gas density. 'I'hirdly, the losses taken care of by the fan are largely copper losses, because of the relative isolation of the field windings from the cooled portions of the sealed casing, although this factor is not essential to the premise. If high pressure gas'is circulated by the fan Bl, particularly in a water-cooled machine, the gas pressure will vary in a ratio of not more than 2 to 1. Furthermore, as the discharge gas pressure varies, the electrical input to the motor 9 changes but little. However, as the suction pressure changes, the

electrical input to the motor l9 changes in a ratio of more than 2 to 1, and the copper loss in a typical calculated case varied in a ratio of nearly 4 to 1. Therefore, it is clear, with the 45 fan 6| circulating high pressure refrigerant gas,

that it is not responsive to changes in load; rather the fan 6| must be so constructed that with the lowest discharge pressure, and, therefore, with the lowest cooling effect on the motor I9, and with the highest suction pressure, and, therefore, with the highest load on the motor, it must circulate sufficient gas for adequate cooling. Then when load decreases due to reduction in suction pressure, the fan will continue to take substantially as much power as before, because the discharge pressure changes but little, and the power input to the fan is, as stated above, proportional to gas density.

If, however, the fan 6| circulates low pressure refrigerant gas, the pressure of which varies with suction pressure, both the cooling effect and the power input, the copper losses varied in the aforesaid ratio of about 4 to 1, which clearly illustrates that the fan 6| automatically takes substantially theexact power necessary to do the workrequired of it. In normal operationafter 75v pull-down during starting of the system, the suction pressure varies in about a ratio of 2 to During pull-down it may vary in a ratio of 4 to 1. In either case, however, the copper losses vary in proportion to the suction pressure. For example, the increase in copper losses in one machine operating between suction pressures of 25 pounds per square inch gauge and 47 pounds per square inch gauge, was 44' per cent. Over the same range of suction pressures, the heat transfer rate varies about 55 per cent. It is obvious, therefore, that as the copper losses inapplication, Serial No. 81,032, filed May 21, 1936, i

v for Compression apparatus, and assigned to the Westinghouse Electric 8; Manufacturing Company.

From the foregoing, it will be apparent that I have provided for an improved cooling system for the heat generating parts of a motor, and particularly for the heat generating parts of a sealed motor-compressor unit for refrigeration applications by circulating refrigerant gas which has been cooled by.contact with the cooled casing of the apparatus over the heat generating portions of the apparatus, to cool the latter.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended .-compressor to the condenser, means for conveying refrigerant vapor from the evaporator to the I compressor, said last-mentioned conveying means communicating with the motor-enclosing portion of said casing, whereby low pressure refrigerant gas at variable pressures dependent upon refrigeration load prevails in the motor-enclosing portion of said casing, and means disposed within said casing and driven by the motor forefiecting forced circulation of the low pressure refrigerant gas between the motor and the wall portions of the casing, so that as the motive power to" drive said motor increases due to refrigeration load and more heatis present to be dissipated, the cooling effect produced by saidcirculating means also increases, and vice 'versa.

-2. In a refrigerating system for variable re- .frigeration loads, the combination of a, compressor, a motor for driving the compressor, said compressor and motor being provided with a fluid-tight enclosing casing, a condenser, an evaporator, means for conveying refrigerant from the compressor to the condenser, means for conveying refrigerant vapor from the evaporator to the compressor, said last-mentioned conveying means communicating with the motor-enclosing portion of said casing, means driven by the motor for effecting forced circulation of refrigerant gas at substantially evaporator pressure between the motor and wall portions of the casing, the density of said gas being controlled by refrigeration load, so that the motive power to drive said circulating means and the cooling effect produced by said circulating means both increase with increases in refrigeration load and decrease with decreases in refrigeration load.

3. In a refrigerating machine for variable refrigeration loads, the combination of a compressor, a motor for driving the compressor, a fluid-tight enclosing casing for the motor and compressor, means for conveying a liquid cooling agent in heat-exchange relation with the walls of the sealed casing, a condenser, an evaporator, means for conveying refrigerant from the compressor to the condenser, means for conveying refrigerant vapor from the evaporator to the compressor, said last-mentioned conveying means communicating with the motor-enclosing portion of said casing, whereby low pressure refrigerant gas at variable pressures dependent upon refrigeration load prevails in the motorenclosing portion of said casing, and means disiiosed within said casing and driven by the mo tor for effecting forced circulation of the low pressure refrigerant gas between the motor and the wall portions of the casing, so that as the motive power to drive said motor increases or decreases with changes in refrigeration load, the cooling effect produced by said circulating means also increases or decreases and the power consumed by the circulating means increases or decreases.

4. The method of cooling the motor of a motor-compressor unit contained in a sealed casing in communication with the low pressure side of a refrigerating system operating at variable refrigeration loads, which method comprises circulating, with a circulating device, low pressure refrigerant gas in contact with the motor, and increasing and decreasing the cooling effect of the circulated low pressure refrigerant gas in re-,

sponse to increases and decreases in refrigeration load. 5. The method of cooling the motor of a motor-compressor unit contained in a sealed casing which is in communication with the low pressure side of a refrigerating system operating at variable refrigeration loads, which method comprises circulating, with a circulating device, low pressure refrigerant gas in contact with the motor, and increasing and decreasing the amount by weight of gas circulated and, therefore, its cooling effect in response to increases and decreases in refrigeration load and, therefore, motor load.

6. The method of cooling the motor of a motor-compressor unit contained in a sealed casing which casing is in communication with the low pressure side of a refrigerating system subjected to varying loads and, therefore, varying suction pressures, which method comprises circulating, with a circulating device, low pressure refrigerant gas in contact with heated portions of the motor, and increasing and decreasing the amount of low pressure gas which is circulated in response to changes insuction pressure.

'7. The method of cooling the motor of a motor-compressor unit contained in a gas-tight casing, which motor-compressor unit is part of a refrigerating system operating at variable refrigeration loads, which method comprises circulating, with a'circulating device, refrigerant gas at substantially the pressure of the low pressure side of the refrigerating system in contact with the motor, whereby the cooling effect of the circulated gas and the power required by the motor vary with the refrigeration load of the refrigerating system.

8. The method of cooling the motor of a motor-compressor unit contained in a gas-tight casing, which motor-compressor unit is a part of a refrigerating system operating at variable refrigeration loads, which method comprises circulating a liquid cooling agent in contact with a wall of the gas-tight casing, and circulating, with a circulating device, refrigerant gas substantially at the pressure of the low pressure side of the refrigerating system in contact with the motor and with said liquid-cooled wall of the sealed casing, whereby the cooling efiect of the circulated gas and the power required by the circulating device vary with the refrigeration load of the refrigerating system.

9. The method of cooling the motor of a motor-compressor unit contained in a gas-tight casing, which motor-compressor unit is a part of the refrigerating system operating at variable refrigeration loads, which method comprises circulating a cooling fluid in heat exchange relation with the motor-compressor unit, and circulating, with a circulating device, refrigerant gas substantially at the pressure of the low pressure side of the refrigerating system in heat exchange relation with both the motor and the cooling fluid, whereby the cooling effect of the circulated gas varies with the refrigeration load of the refrigerating system.

10. In a refrigerating system, the combination of an evaporator, a condenser, a compressor for circulating refrigerant gas from the evaporator to the condenser, a motor for driving the compressor, a fluid-tight casing enclosing the motor and the compressor, means for admitting refrigerant gas circulated by the compressor to the motor containing portion of the casing, means for circulating a cooling medium in heat exchanging relation with the motor containing portion of the casing, and means driven by the motor for forcibly circulating refrigerant gas in the casing in heat exchanging relation with said cooling medium and with heated portions of the motor to abstract heat from the latter.

11. In a refrigerating system, the combination of an evaporator, a condenser, a compressor for circulating refrigerant gas from the evaporator to the condenser, a motor for driving the compressor embodying gap therebetween, a fluid-tight casing enclosing the motor and compressor, means for admitting refrigerant gas circulated by the compressor to the motor-containing portion of the casing, and

means driven by the motor for forcing the gaspresent in said casing through said gap of the motor to absorb heat from the latter.

12. In a refrigerating system, the combination of an evaporator, a condenser, a compressor for circulating refrigerant gas from the evaporator to the condenser, a motor for driving the compressor, a sealed casing for totally enclosing the motor and compressor, a motor compartmentinwhichthe motor is disposed and a compressor compartment in which portions of the compressor are disposed, said motor embodying a stator and a rotor, said stator being pressed into the motor portion of the sealed casing and directly contacting portions of the interior surface thereof, said stator being spaced from other portions of the sealed casing to provide for passages extending longitudinally of the stator, said rotor being provided with passages extending longitudinally thereof, means for admitting refrigerant gas circulated by said coma stator and a rotor with a pressor to the motor compartment of said casing, means for circulating cooling medium in heat exchange relation with the casing, and means driven by the rotor for circulating the refrigerant gas in the casing in heat exchange relation with said'cooling medium and through the passages between the stator and the casing and the passages in the rotor to absorb heat from the stator and the rotor.

13. The combination as claimed in claim 12 wherein the sealed casing is in open communication with the evaporator of the refrigerating system whereby refrigerant gas at substantially suction pressure prevails within the sealed casmg.

14. In a refrigerating system, the combination of an evaporator, a condenser, a compressor for circulating refrigerant gas from the evaporator to the condenser, a motor comprisinga stator and a rotor for driving the compressor; a fluidtight casing enclosing the motor and the compressor, means providing communication between the inlet of the compressor and the-motor-conelement carried by said. rotor and effecting flow of refrigerant gas from one end of said motor to the other in contact with said stator and back to said one end in contact with said rotor.

15. In a refrigerating system, the combination of an evaporator, a condenser, a compressor for circulating refrigerant gas from the evaporator to the condenser, a motor for driving the compressor, a fluid-tight casing enclosing the motor and the compressor, said motor embodying a stator and a rotor, portions of said stator being disposed in contact with the inner surface of said casing and other portions being spaced from said inner surface to provide refrigerant gas, the portion of said casing adjacent said first-mentioned stator portions and said passages being provided with a cooling water jacket for cooling the motor, means for admitting refrigerant gas circulated by said compressor to the motor containing portion of the casing, and means driven by-the rotor for circulating the refrigerant gas in the motor containing portion of the casing through the pwsages between the casing and the stator to cool the gas and in contact with heated portions of the motor to abstract heat therefrom.

EDWARD R. WOLFERT. 

